[Spatial heterogeneity of soil moisture in Shapotou sand-fixing artificial vegetation area]

To explore the characteristics of soil moisture heterogeneity in sand-fixing artificial vegetation area is of significance in vegetation recovery and environment control in arid regions. With the methods of traditional statistics and geo-statistics, this paper studied the heterogeneity of soil moisture in the layers from 0 to 200 cm in depth in Shapotou sand-fixing vegetation area. The results showed that the variation of soil moisture in layers of 160 to approximately 180 and 180 to approximately 200 cm was relatively larger, with the variation coefficient being 0.72 and 0.73, respectively, and the next was in top layer (0 to approximately 5 cm ), with a variation coefficient of 0.66. Semi-variance analysis showed that the autocorrelation of soil moisture spatial heterogeneity in total spatial heterogeneity was high, ranging from 87.7% to 99.9%. The scale of spatial heterogeneity in different soil layers was different, with the minimum in 60 to approximately 80 cm layer and the maximum in 20 to approximately 40 cm layer, but no regular changes being observed from surface to deep layers. The colorful contour maps of Kriging interpolation indicated that the variation of soil moisture was larger in 0 to approximately 140 cm layer than in 140 to approximately 200 cm layer. The correlation between semi-variance and distance in four directions of 0 degrees, 45 degrees ,90 degrees and 135 degrees was weak, suggesting that the variation of soil moisture was independent, random, and homogeneous.